1. Installation Issues:
* Incorrect Installation: The most common reason. Was it installed correctly? This includes proper connection of wires, grounding, and ensuring the pump is seated properly in the tank. A simple wiring error can render it useless. Double and triple check the wiring diagram.
* Damaged Pump During Installation: It's possible the pump was damaged during the installation process. A dropped pump or mishandling could cause internal damage.
* Damaged Fuel Tank: The fuel tank itself might have damage that's preventing the pump from functioning correctly – perhaps a crack or debris interfering with the pump's movement.
* Loose or Damaged Connections: Check all electrical connections for corrosion, loose wires, or broken connectors. Even a slightly loose connection can disrupt the pump's operation.
2. Fuel Pump Issues (despite being new):
* Faulty Pump (despite being new): Unfortunately, even new parts can be defective. It's rare, but it happens.
* Incorrect Pump: Did you get the correct pump for your specific Wrangler model and engine? There can be variations.
* Pump Wiring Harness Issues: The wiring harness connecting to the pump might be damaged or have a short circuit, even if the pump itself is fine.
3. Other System Problems:
* Fuel Filter: A clogged fuel filter can prevent fuel from reaching the pump, preventing it from priming and working. Replace this as a preventative measure.
* Relay: The fuel pump relay might be faulty. This relay is what switches power to the pump. Test it using a multimeter or swap it with a known good relay (from a non-essential circuit if possible).
* Fuel Pump Fuse: Check the fuel pump fuse. A blown fuse will prevent power from reaching the pump.
* Inertia Switch: Some vehicles have an inertia switch (often under the dashboard) which cuts power to the fuel pump in a crash. This switch needs to be reset (usually by pushing a button) if it's tripped.
* Computer/ECM Issues: While less likely, a problem with the vehicle's computer could be preventing the pump from receiving the signal to turn on. This would require diagnostic tools.
* Low Fuel Level: While sounding obvious, sometimes a very low fuel level can cause a pump to have problems drawing fuel and/or fail to prime.
Troubleshooting Steps:
1. Check Fuses and Relay: Start with the easiest checks: fuse and relay.
2. Visual Inspection: Carefully inspect all wiring and connections related to the fuel pump.
3. Fuel Pressure Test: This is the most definitive test. You need a fuel pressure gauge to measure the pressure at the fuel rail. Low or no pressure indicates a fuel delivery problem.
4. Check the Inertia Switch: If equipped, reset it.
5. Verify Wiring: Trace the wiring from the pump to the relay and power source, checking for continuity.
If you are not comfortable working on your vehicle's fuel system, take it to a qualified mechanic. Fuel systems can be dangerous if handled improperly. They work with flammable and pressurized fuel.
